Electric fuse for projectiles



y H. RUHLE MA NN ELECTRIC FUSE FOR PROJECTILES Filed Jan. 6, 1928 l/ r l rf fiu'lllemaznaf Patented May 7, 1929.

UNITED STATES I PATENT OFFICE.

HERBERT RfTHLEIV IANN, F SOMMERDA, GERMANY, ASSIGNQR TO RHEINISCHE METALL'WAAREN- UNI) MASCHINENFABBIK, OF DUSSELDORF-DERENDORF, GER- MANY,A CORPORATION OF GERMANY.

ELECTRIC FUSE FOR PROJECTILES.

Application filed January 6, 1928, Serial No.

- The invention relates to an electric fuse intended for projectiles and in which the discharging energy of an electric condenser is used to ignite thecomposition. The inven- 6 tion has for its object to make the fuse safe in the gun barrel by means of a special connection ofthe condenser, all mechanical safety appliances being obviated.

According to my invention the fuse com- 10 prises two condensers, the equally-loaded Q coatings being connected with each other and two thereof to the composition, which condensers are loaded up from a source of ourrent to equal voltage, one of them discharg- 16 ing, after the projectile has been fired,

through a resistance, so that only after a certain flight of the projectile a voltage arises between the two poles of the two condensers that sufiices to ignite the composition.

The composition may be heated up to the degree of heat required for the ignition either by means of a heating wire embedded therein and through which the current flows, or by the spark of a spark gap formed between two poles, arranged at a distance apart from one another, of the conduit leading to the condensers. A permanent magnet arranged in known manner in the fuse may serve as source of current, which magnet, according to the fuse is a time fuse or impact fuse, generates an induction current, in a coil connected with the condensers, by its movement relatively to this coil provoked due to the shot is being fired or the target being hit. The condensers may also be loaded by a source of power arranged separately from the projectile, which measure may also be adopted with all condenser fuses, of other design and affords a very simple electric fuse that occupies but little space.

In order to allow of my invention to be more easily understood, two preferred embodiments of my improved fuse are diagrammatically illustrated in the drawing which accompanies and forms partof this specification. In this drawing:

Figure 1 is a diagrammatic view showing the electric connections of a fuse, the source of current is formed by a permanent magnet, Figure-2 indicates the curves of voltage and time,

Figure 3 is a view of a fuse the condenser the shot being fired 244,932, and in Germany January 14, 1927.

of which is loaded from a source of current arranged separately from the fuse.

In the embodiment shown in Figure 1, the permanent magnet a is ada ted to be shifted in the longitudinal axis 0 the projectile in the coil 6. The one end of coil 12 is connected 'to the conduit e that interconnects one coating of each of the two condensers c and d. The

other end of coil 6 is connected to the other coatings of the condensers c and d at the points is and Z by' the conduits h and '5 through the contacts f and g. The points k and l are in connection with one another by the conduit 0 through an igniting wire nembedded in the composition m, a contacter p, p, being arranged in conduit 0. The contacter p, p, is designed so as to be closed only when the projectile hits an aim, this being efl'ected e. g. by the inertia of one of the contact plates or by the resistance of the air hit. The two coatings of the condenser d are further connected through a high ohm-resistance When the projectile is fired,-the magnet a is forwarded through the coil 6 due to the inertia of its mass and generates an induction current in the coil, by which current the two condensers c and d are loaded with equal voltage. At the end of its motion, magnet on opens the contact f and g whereby the loaded condensers are disconnected from coil 6 As the condensers c and d are loaded in parallel to one another, no difference of potential exists at the points 70 and Zimmediately after the load. Hence, if immediately after the shot has been fired, that means when the projectile is still in the gun barrel, or close in front of it, the impact contacter p, p, would be closed by any reason, no current flows through the ignition wire 1 and no ignition takes place, as the same potential prevails at the points In and Z.

After being loaded, the one condenser, (E, discharges rather quickly through the resistance q, whilst the condenser closes only quite successively some of its voltage due to the incompleteness of its dielectrics. These phenomena are illustrated in Figure 2 for the condenser c by the voltage-time curve 1', and by the curve 8 for the condenser d. Upon (t=zero) both condensers have the voltage E, at the moment t,

closed unintentionally, would not be highenough yet, to send from condenser to condenser d a current through the heating wire I n, that would be suflicient to immediately ignite the composition m. Only when a further equalization of the two condensers takes place, also through the resistance q, the wire n would be heated in this ease up to the temperature required to ignite the composition, which heating would take place only gradually. After the moment t the potential difference E '-E of the condensers a, d has become so great, that when the contacter p, 1), would now be-closed, an immediate ignition of the composition takes place b the current equalizing through the latter. he resistance 9 and therewith the discharge of condenser d is so tuned, that at the moment t,, that iswhen a suflicient potential difference already 'prevails between the condensers p and d, the projectile is already at a sufiicient distance from the gun barrel, so that an eventual premature closure of the contacter p, p, and the subsequent immediate ignition of the composition afiords no danger for the crew and the gun. As it will be seen from the foregoin my improved purely electrically operate imas only after the shot electric-ignition ower is supplied to it, but is also safe within the gun arrel, as only after the projectile has left the gun barrel a current of a voltage required to immediately ignite the composition is generated and sent through the latter, and finally, my fuse is of a very high sensibilit as the impact contacter may be-closed alrea y by a ver slight force and as the delay arising in the e ectrie equipment, after the contacter has been closed, is extremely small.

Instead of by the igniting wire 1, the composition m may also be ignited by means of a spark gap formed in the conduit 0. To this end the conduit 0 including the composition m is interrupted. However, a spark can be produced in the composition after the contacter p, 1;, has been closed, only after a determined potential difierence has arisen between .the points Jo and Z after the discharge ofcondenser d through the resistance q.

The resistance 9 through which the con,- d'enser d is discharged, may further be designed so as to be regulated. In this manner the discharge time of condenser d is made adjustable and a barrel-safe fuse is obtained, as thus the voltage required to ignite the composition arises after a shorter or longer lapse of time according to the amount of resistance,-

adjusted on the resistance q between the poles k and Z interconnected through, the composi;

tion m. A spark gap is advantage'ouslyar ranged in this case-in the composition m in the conduit 0 leading to the condensers. The impact contacter p, 1), arranged in conduit 0 is then dispensed with, but the wiring in o l is closed from-the first, except said spark gap.

When the ignition of the composition m is effected by means of a spark gap, then in order to differently adjust the ignition moments, the. two poles located in the composition andleading to the condensers c and d,

-. arise after a shorter or longer lapse of time.

The impact fuse the wiring diagram of which is illustrated in Figure 3, is loaded from a source of current arranged separately from the projectile, the other electric equipment and mode of operation of the fuse corresponding to that of the first embodiment. A separate generator or a cell may serve as source of current. To load the fuse, e. g. the

conduit 0 that immediately connects one coating ofeach-of the two condensers c and d, is connected to the minus pole, and the: wires h and 2' leading to the other coatings of the condensers are connected to the plus pole of the source of current. With a time fuse, the pact fuse 1s not only safe during transport,

"loading of the condensers may take place upon the projectile being introduced in the gun barrel. or, with a suitable connection of said contact pieces with the trigger mechanism. only when the projectile is fired.

If the source of current'is separated from the projectile, a switch is arranged in the conduit connecting the condenser d of the fuse through the resistance g, which switch connects the condenser automatically only upon the shot being fired, in order to obviate that the condenser d, eventually loaded before theshot, already discharges likewise before the shot.

What I claim, is j p 1. In an electric ignition device for proiectiles, a source of electric current, an igniting composition, two electric condensers adapted to be loaded "said source of current and the equally-loaded coatings being connected with each othqr, and two thereof jectiles, a source of eleetriccurrent, an igniting composition, two electric condensers adapted to be loaded by said source of current and the equally-10a coatings being connected with each other and twothereof to rent and the equally loaded coatings being the composition, and a high-ohm resistance connected with each other and two thereof to 10 interconnecting the two coatings of one of the composition, and a high ohm regulating said condensers. resistance interconnecting the two coatings 5 3. In an electric ignition device for proof one of said condensers.

jectiles, a source of electric current, an ignit- In testimony whereof I have affixed my ing composition, two electric condensers signature.

adapted to be loaded by said source of cur- HERBERT RUHLEMANN. 

